Unit 7 - Integumentary System - Library


Unit 7 - Integumentary System - Library

Unit 7 - Integumentary SystemUNIT OBJECTIVES1. Define the terms: dermatology and homeothermic.2. Identify at least five functions for the integumentary system.3. Locate the skin’s three major layers and identify a function for each.4. Locate the five layers of the epidermis and identify a function for each.5. Identify the function of keratin and describe keratinization.6. Locate and identify a function for each of the following epidermal structures:basal cells, nail, nail matrix, cuticle (eponychium), hair (pili), hair root, hair shaft,hair follicle, bulb, follicular papilla, hair matrix, and arrector pili.7. Locate the following glands, identify their function, and the functions of theirsecretions: sudoriferous glands, ceruminous glands, mammary glands, andsebaceous glands.8. Locate and identify a function for each of the following connective tissue structures:dermis, papillary region, dermal papilla, reticular region, subcutaneoustissue, and adipose tissue.9. Explain how each of the following affects skin color, locate these factors, andrelate each to the function of skin: melanin, hemoglobin, and carotene.10. Explain how MSH causes tanning.11. Explain the probable causes of freckles, albinism, and vitiligo.12. State the normal value for body temperature and explain how the hypothalamusand blood temperature are involved in maintaining this value.13. Explain how each of the following is involved in temperature regulation: BMR,chemical thermogenesis, thyroxine, epinephrine, norepinephrine, shivering,vasomotor response, adipose tissue, hair, radiation, and evaporation.14. Define the terms chills and fever and identify their purpose.NOTESI. Dermatology is the study of skin. Skin forms the body’s integumentary system.This system is the barrier that separates the body’s internal parts from theexternal environment.A. The integumentary system has many important functions. Some of thesefunctions are:1. It protects the body against: mechanical injury (i.e., abrasion), chemicalinjury (i.e., acid), ultraviolet radiation, and microbial invasion (i.e., bacteria).2. It aids in regulating water content and body temperature.3. It aids in excreting metabolic wastes.4. It produces vitamin D from cholesterol when exposed to light.5. It collects data about the external environment.B. The integumentary system is a cutaneous membrane. Like all epithelialmembranes, it consists of an epithelium and a connective tissue. This structureis organized into three layers called the epidermis, dermis, and subcutaneouslayer.II. The skin’s epithelial tissues form its epidermis and glands. Let’s examine thesestructures more closely.A. The epidermis is the outermost layer of the skin. Because this layer alsoforms the epithelial tissue of the skin’s cutaneous membrane, it is attachedto its underlying connective tissue by a basement membrane. The epidermisis composed of a stratified squamous epithelium that can be either keratinizedor nonkeratinized.1. The epidermis has five distinct strata or layers of cells. These layers arethe: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum,and stratum corneum.a. The deepest epidermal layer is the stratum basale or stratum germinativum.This layer is attached to the basement membrane and it consistsof one row of columnar cells. These cells may be basal cells orMerkel’s cells.1. Basal cells form most of the stratum basale. These cells are responsiblefor the production of new epidermal cells because they get59

Unit 7 - Integumentary Systemmost of the nutrients coming into the epidermis. As the new cells arereplicated, they are pushed upward.2. The stratum basale possesses only a few Merkel’s cells. Thesecells are neurons that are sensitive to touch.b. The stratum spinosum lies just above the stratum basale. This layerconsists of eight to ten rows of transitional cells.c. The middle epidermal layer is called the stratum granulosum. Thestratum granulosum is composed of three to five rows of squamouscells called keratinocytes. Keratinocytes produce keratin by a processcalled keratinization. The granulosum’s keratinocytes begin this processby producing and storing a molecule called keratohyalin. Becausethis molecule has keratin’s basic structure, it can be transformed intothis waterproofing protein.d. The stratum lucidum lies just above the stratum granulosum. Thisskin layer is composed of three to four rows of keratinocytes. Thesecells continue keratinization by transforming keratohyalin into eleidin.Like keratohyalin, eleidin is not secreted. It is stored.e. The stratum corneum is the outermost epidermal layer. It is composedof about 30 rows of dead keratinocytes that are impregnatedwith keratin. The keratin is formed, when the cell’s eleidin deposits areexposed to the air.2. Besides forming the epidermis, some epidermal cells specialize to formnails. Nails are modified epidermal cells that protect the distal ends ofthe digits. These structures also improve the dexterity of the fingers byenabling them to grasp small objects. A nail is produced from its root by alayer of cells called a nail matrix. This reproductive layer lies deep to thenail’s cuticle or eponychium.3. Pili or hair is also formed from modified epidermal cells. These specializedstructures assist the body in regulating its temperature. They alsoprotect the body from mechanical injury. Let’s examine the function andstructure of hair more closely.a. Each hair has a root and a shaft. The hair’s root is embedded in theskin’s dermis, while its shaft extends beyond the skin’s surface.b. The hair’s root is surrounded and protected by a cylinder of modifiedepidermal cells called a hair follicle. Both the follicle and the root enlargeat their base to form a bulb. This swollen structure anchors thehair to the skin. The bulb contains a follicular papilla and a matrix.c. The follicular papilla is at the base of the bulb. This bump-like structurecontains blood capillaries and nerves. The papilla’s nerves aresensitive to touch, while its capillaries provide nutrients to the hair’smatrix. A hair’s matrix borders its follicular papilla. These cells are responsiblefor producing the hair.d. Because each hair is closely associated with the nervous system, hairis very sensitive to touch. This sensitivity is enhanced by the length ofthe hair’s shaft. Because a hair’s shaft extends beyond the skin’s surface,it enables the body to avoid some injuries.e. Hair shafts also help to regulate the body’s temperature. This is possiblebecause of arrector pili. Arrector pili are strips of smooth musclesthat attach to a hair’s follicle. When the body gets chilled, the arrectorpili fluff the hair (causes goose bumps). Since air is an excellent insulator,goose bumps warm the body because fluffed hair has more airtrapped underneath it.B. There are four types of glands associated with skin: sudoriferous glands,ceruminous glands, mammary glands, and sebaceous glands. Let’s examinethese glands and their roles.1. The skin’s sudoriferous glands are embedded in its dermis. These exocrineglands produce sweat through a process called sweating or perspiration.Sweat is a mixture of salt, water, amino acids, and wastes (i.e.,uric acid, ammonia, and urea). Sweating is valuable because it enablesthe body to regulate its temperature through evaporation. To a lesser degree,sweating also removes metabolic wastes. Temperature regulationwill be covered in more detail later in this unit.2. The skin’s ceruminous glands are modified sudoriferous glands. Theseglands are located in the external auditory meatus (ear canal) and theysecrete a waxy material called cerumen. Cerumen (earwax) preventsbacterial invasion because it is very sticky.3. Mammary glands are modified sudoriferous glands that are located inthe breasts. These exocrine glands are responsible for producing milk.This watery fluid provides nourishment to a baby early in its development.4. The skin’s sebaceous glands attach to its hair follicles. These exocrineglands secrete an oil called sebum. Sebum is a mixture of fat, protein,and salt. This secretion keeps the hair and skin soft and pliable.III. The skin’s connective tissues form its dermis and subcutaneous layer. Let’sexamine these regions more closely.A. The skin’s dermis lies just beneath its epidermis. This loose connective tissuecontains both collagen and elastic fibers. The dermis has two distinctlayers: the papillary region and the reticular region.60

Unit 7 - Integumentary System1. The papillary region lies next to the basement membrane of the epidermis.This region contains large numbers of dermal papillae. Thesebump-like structures increase the surface area between the epidermisand the dermis. This additional surface area enhances the exchange ofnutrients between these layers.2. The reticular region lies between the skin’s papillary region and its subcutaneouslayer. In comparison with the papillary region, the reticularregion’s loose connective tissue contains a higher concentration of elasticand collagen fibers. Therefore, the reticular region gives the skin flexiblestrength.B. The subcutaneous layer is the innermost layer of the skin. This layer consistsof a loose connective tissue that contains a high concentration of adiposetissue. This composition enables the subcutaneous layer to help theskin regulate body temperature because it functions as insulation.IV. Skin coloration is influenced by three primary factors: melanin concentration,blood circulation, and carotene concentration.A. Melanin is a dark pigment found within the skin’s epidermis. Although thispigment determines the skin’s darkness, its primary function is to preventsunburn. Melanin does this by filtering harmful ultraviolet radiation. Note -Exposure of the skin to some ultra-violet light is good. The skin uses thislight to manufacture vitamin D from a form of cholesterol.1. Melanin is produced by the melanocytes of the stratum basale. Melanocyteactivity is controlled by the pituitary gland through melanocytestimulating hormone (MSH). MSH stimulates the melanocytes to produceand disperse melanin. The body regulates the pituitary’s MSH secretionby monitoring its exposure to light.2. When stimulated by MSH, melanocytes produce cytoplasmic extensionsinto the upper epidermis. These extensions are filled with melanin. Epidermalcells obtain the melanin by phagocytosis. The skin tans, as thecells darken.3. Melanin may not be uniformly dispersed throughout the skin. This unequaldistribution is responsible for several color abnormalities.a. Some people have difficulty dispersing melanin throughout their skin.In these people, melanin remains in small clusters. These abnormalitiesare called freckles.b. Some people lack the ability to produce melanin. These people arevery pale. Because melanin contributes to hair color, these people alsohave white hair. This condition is called albinism and it is a conditionfound in albinos.c. Some people have patches of skin that lack melanocytes. Thesepatches appear white because they lack melanin. This condition iscalled vitiligo.B. Melanin may not be concentrated enough to mask the skin’s pink color. Thiscolor is caused by hemoglobin found in the blood of the dermis. Thegreater blood circulation within the skin, the greater the hemoglobin concentrationand the pinker the skin.C. Carotene is responsible for the yellowing of skin. This pigment is a form ofvitamin A. Because carotene is fat soluble, it is concentrated in the subcutaneouslayer’s adipose tissue.V. Maintaining a constant body temperature is important for good health becauseheat affects body chemistry. Animals that maintain a constant temperature aresaid to be warm-blooded or homeothermic. Humans are homeothermic becausethey try to maintain a temperature of 98.6 o F. Let’s examine this importanthomeostatic mechanism.A. To maintain body temperature, heat loss must equal heat gain. This delicatebalance is affected by many factors: metabolic rate, sweating, muscularmovement, blood circulation, etc. The brain’s hypothalamus controls manyof these factors in its efforts to regulate to body temperature. This is accomplishedthrough negative feedback. The hypothalamus bases its decisionson the temperature of the blood. If blood temperature is abnormal, the bodyadjusts the temperature by controlling the production and conservation ofheat. This is achieved in several ways.1. The primary way to control the body’s temperature is by adjusting itsBMR. This is a good source of heat because cell respiration traps onlyabout 45% of its energy in ATP. The rest of the liberated energy is lost asbody heat. Therefore, adjusting the BMR controls the amount of heatgenerated. This is called chemical thermogenesis. The hypothalamusregulates the body’s BMR by controlling the secretion of thyroxine, norepinephrine,and epinephrine. These hormones increase the body’s BMR.2. The body can also adjust its temperature by controlling the activity withinits skeletal muscles. Shivering (intense muscle activity) raises body temperaturebecause it increases chemical thermogenesis.61

Unit 7 - Integumentary System3. Blood transports and disperses most of the body’s heat. Therefore, controllingthe flow of blood has an effect on body temperature. Control ofblood flow is achieved by adjusting the vasomotor tone (diameter) of thebody’s blood vessels.a. If the body is cold, the vasomotor center of the brain will constrict theblood vessels leading into the skin. This vasoconstriction will trapblood deeper within the body, making it more difficult to lose heat byradiation.1. Radiation is a process in which an object gains or loses heat toanother object without direct contact (i.e., being in the same roomwith a frozen radiator). When vasoconstriction occurs within theskin, radiation decreases because body heat must travel farther toescape.2. The escape of heat is also slowed by adipose tissue. This tissueenhances the effects of vasoconstriction because it insulates theskin’s subcutaneous layer.b. If the body is warm, vasodilation will occur within the skin. This enablesthe body to dissipate the heat, cooling it.4. If additional cooling is necessary, the body will begin to sweat. Sweatingpermits evaporation to occur. Evaporation is the conversion of water intowater vapor. This cools the body because water has lots of heat trappedwithin its molecules (it’s polar covalent). Therefore, as water vapor leavesthe body, it takes heat with it.B. Like any homeostatic mechanism, body temperature will fluctuate becauseof stress. Chills and fever are two of the more common temperature abnormalities.INTEGUMENTARY SYSTEM SELF QUIZFill-in the Blank1. The stratum ______ initiates keratinization.2. _____ is the waterproofing protein of the skin.3. The _____ _____ is responsible for feeding the hair.4. The hair is lubricated and condition by _____.5. Tanning is stimulated by _____ _____ _____.6. _____ functions in protecting the skin from ultra-violet radiation.7. Cold causes the hair to stand on end, this is accomplished by the _____ _____muscle.8. Most of the body’s heat is lost through _____.9. The skin can remove waste products by using its _____ glands.10. The stratum _____ is responsible for producing most of the cells in the epidermis.11. An inability to produce melanin is caused a condition called _____.12. _____ is a substance that protects the ears from bacterial invasion.13. Most of the skin’s adipose tissue is located within a region called the _____.14. ____ is a condition characterized by white patches on the skin.15. Most of the body’s heat is generated by a process called _____ _____.16. Body heat can also be conserved by diverting blood away from the skin througha process called _____.17. The outermost layer of the epidermis is called the _____ _____.18. _____ is the study of the skin.19. A hair is contained within a structure is called a _____.20. _____ is a pigment that causes a yellowish tint to the skin.Answers in Appendix A1. Sometimes, the body needs a tremendous amount of energy to cope withits problems (i.e., fighting an infection). This energy is supplied by anextraordinary increase in the body’s BMR. Besides producing energy, anelevated BMR also generates an abnormally high body temperature. Thisresponse is called a fever.2. Chills are characterized by shivering and cold, clammy skin. Becauseshivering and vasoconstriction elevates body temperature, the body useschills to initiate its fevers.62

Unit 7 - Integumentary SystemIntegumentary Crossword1 2 3 4 5 6 7 8 9 1011 12 13 1415 16 17 1819 20 2122 23 24 2526 27 28 29 30 3132 33 34 3536 37 38 3940 41 42 4344 45 46 47 4849 5051 52 53 54 5556 57 5859 60 61 6263 64 6566 67 68 69 70 7172 73 74 7576 77 78 79 8081 82 83 84 8586 8788 89 90ACROSS1 the integument3 transfer of heat to an object by direct contact8 a measure of oxygen consumption while at rest abbr.11 alien movie abbr.12 to laugh13 elemental symbol for sodium abbr.14 nude15 disorder of people who lack melanin18 small clusters of melanin within the skin19 auditory organ21 not odd22 Soviet space station23 dirt26 swelling28 body of saltwater29 eponychium31 to exist32 building block of life33 negative35 gluteal36 name37 this person is typically pale with white hair and pink eyes39 particles forming matter41 business acronym43 detective abbr.44 pigment which yellows the skin46 enables sweating to effectively cool the body50 main artery of the body51 Washington weather52 outer skin layer55 bringing up the rear56 found within follicles57 to be fond of oneself59 most important60 farther from the body's surface62 soft waterlogged ground63 prefix meaning two65 water marker66 National Education Association69 this stratum initiates keratinization71 graduate business degree abbr.72 part of a play74 opposite of off76 made from ammonia77 dermal region which feeds the epidermis81 layers84 used to sell an item in a newspaper85 dry86 to vend63

Unit 7 - Integumentary System87 thick fluid containing dead leukocytes and debris88 type of movement which does require NET use of energy by the cell89 in the morning abbr.90 this nitrogen base pairs with thymineDOWN1 street abbr.2 not in homeostasis3 used to generate heat4 Organization of American States abbr.5 the outermost layer of the epidermis6 linear measurement7 deciduous tree8 a material which liberates hydroxide ions when it ionizes9 male title abbr.10 type of bone marrow involved in blood production11 matter composed of only one type of atom14 to exist15 fluffs the hair (2 wrds)16 this stratum is also called the germinativum17 protects the skin from ultraviolet rays18 mineral used to make hemoglobin abbr.20 to help24 the study of skin25 this is the reproductive stratum of the skin27 singer Torme30 to furnish food31 elemental symbol for barium abbr.34 opening to a story: _____ upon a time38 prefix meaning two40 the connective tissue layer of the skin42 helps to insulate the body43 not pans44 earwax45 this chemical hardens to become keratin47 organization used to rehab drunks abbr.48 savings pension abbr.49 an assistant53 hormone that stimulates tanning abbr.54 this oil conditions the hair shaft58 Gomer’s brother61 a prefix used to designate an apoenzyme63 newsman Rather64 this layer produces eleidin from keratohyalin67 pinnae68 acid which is needed to synthesize citric acid70 this anchors a hair73 pitch75 a negatively charged particle77 hair78 Mama’s mate79 a material which liberates hydrogen ions when it ionizes80 a tall tale82 famous boxer83 typical suffix for an enzyme using modern nomenclatureAnswers in Appendix B64

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